Mixpanel: real-time analytics

Unlike Google Analytics, Mixpanel isn't for tracking aggregate data about page views. Instead, you send specific events to Mixpanel when users perform certain actions. This allows you to examine how users interact with your site in real-time and connects all events to the individual user who performed them (so you can contact them).

Mixpanel is great for finding ways to improve usability, studying how existing features are actually used and is especially good for startups who are trying to refine their MVP (Minimum Viable Product).